RFR: 4459231: Focus of JTabbedPane(with Scrollable tablayout) changes on change in LookAndFeel [v3]

[Prasanta Sadhukhan]

> On changing LookAndFeel of JTabbedPane, it resets the focus of the child tabs to starting child tab.
> That is, if a JTabbedPane has say 10 tabs and we select the 10th tab and then we change the L&F, the focus is shifted to Tab0 even though the selected tab is still at 10th tab.
> 
> This is because when we switch L&F, `installUI ` will reset the `focusIndex ` 
> https://github.com/openjdk/jdk/blob/3481252ced7c06c44154ceccc56b12cfd9a490c3/src/java.desktop/share/classes/javax/swing/plaf/basic/BasicTabbedPaneUI.java#L285-L290
> 
> which needs to set the proper focus by calling `scrollRectToVisible ` to selected tab which is done in this fix.

Prasanta Sadhukhan has updated the pull request incrementally with one additional commit since the last revision:

  Test fix

-------------

Changes:
  - all: https://git.openjdk.org/jdk/pull/28571/files
  - new: https://git.openjdk.org/jdk/pull/28571/files/f110cc52..f4c0db8b

Webrevs:
 - full: https://webrevs.openjdk.org/?repo=jdk&pr=28571&range=02
 - incr: https://webrevs.openjdk.org/?repo=jdk&pr=28571&range=01-02

  Stats: 4 lines in 1 file changed: 2 ins; 1 del; 1 mod
  Patch: https://git.openjdk.org/jdk/pull/28571.diff
  Fetch: git fetch https://git.openjdk.org/jdk.git pull/28571/head:pull/28571

PR: https://git.openjdk.org/jdk/pull/28571